At Kandykween: consider what happens if white is allowed to move his advanced pawn to the eighth rank and promote it to a queen. What is stopping white from doing this?

I looked at the puzzle again and now I get it! It would be a check, right? And the black queen would take and the whole thing would collapse, right? So... the white queen baits the black queen... but the black queen doesn't take because... um... (I'm sorry I'm stupid at this!) it would be checkmate because the black queen wouldn't be protecting/guarding the square, so white would promote and it would be checkmate?

Why would the black queen not take the white queen? Also, with a white pawn on the verge of queening, I kept trying to use it. And if in the end you're just going to end up winning by putting the queen up there and taking the other queen, couldn't you do that in two moves by moving the queen up in the first move? Counter intuitive, but a very creative puzzle.

Checking with the queen on the back rank on the first move doesn't work because the king still has an escape square. After it moves to g8 to avoid the first check, it can't escape anymore.

By offering up the Queen to remove it from defending a key square on the bank rank are we employing the concept of DECOY or DEFLECTION? Anyone know the "proper" answer? I know they are similar. Wondering what the defining difference is between the terms.

I've only heard the term "deflection" used for a situation where a piece is enticed or forced from the defense of a key square/diagonal/rank/file. I would guess "decoy" means the same thing but isn't as widely used.

Edit: Actually according to wikipedia, a decoy is when you lure a piece to a specific bad square, whereas a deflection lures it to any square where it can no longer adequately defend the threat. So a decoy would be a specific type of deflection (if I understood it correctly).